Piston expanding device



Patented Mar. 7, 1950 PISTON EXPANDING DEVICE George C. Mayfield,Richmond Heights, Mo., as-

signor to McQuay-Norris Manufacturing Company, St. Louis, Mo., a c

Application October '7, 1948, Serial No. 53,305

Claims.

This invention pertains to expanders, such as are used to enlarge thediameters of pistons for internal-combustion engines to fit the pistonto the cylinder. Such pistons are often heat-treated in their expandedcondition, so as to set the metal permanently in its new shape.

One of the objects of this invention is to provide an expander which maybe operated to expand the piston skirt at either its upper or its lowerend, or both.

Another object is to provide such an expander of novel construction,which shall be rugged,. but easily manipulated.

Another object is to provide such an expander with a novel type ofexpanding element.

Another object is to so construct the device that the same expandingelement may be manipulated to expand the upper or the lower portion ofthe piston, or both.

Further obiects will appear from the following description, taken inconnection with the accompanying drawing, in which will be set forth anillustrative embodiment of the invention. It is understood, however,that this invention is susceptible of various embodiments, within thescope of the appended claims, without departing from the principle orspirit of the invention.

In the accompanying drawing:

Figure 1 is a side view, with parts broken away, of an expanderembodying this invention, shown as applied to a piston, the latterpartly in section;

Figure 2 is a section on line 2--2 of Figure 1;

Figure 3 is a fragmentary view, similar to Figure 1, showing theapplication to a modified type of piston;

Figure 4 is an enlarged detail of the expander chain;

Figure 5 is a side view of a length of the expander chain, illustratinga certain degree of flexibility; and

Figure 6 is a partial section on line 6-6 of Figure 1.

Referring now to the drawing, I designates genorporation of Delawareerally a supporting body on which the other parts of the assembly may becarried. The body I includes a base 2, a pair of side plates 3 mountedon the base 2 by screws 4 and dowels 5, and an expandable head 6.Threaded through the base 2 is an operating element I in the form of asleeve, which is connected to the head 6 as will be more fully describedhereinafter. Extending through the sleeve 1 is another operating element8. This latter element comprises an internally threaded sleeve, engaginga correspondingly threaded rod. 9 having an enlargement It bored out tofit over the piston-pin I I of the piston I2, which is to be expanded.

The expanding element is in the form of a chain I3. In the embodimentillustrated, this is in the form of a sprocket chain of the silent type,such as is used for timing chains in internal-combustion engines. Suchchains have the special property that the pivots between the links aredesigned to permit only a limited pivotal movement. This makes the chainstiif, so that it will not bend in an arc of less than a certain minimumradius in one direction, and. usually will bend only very slightly inthe opposite direction. This is illustrated in Figure 4, in which thedotted positions of the right-hand link indicate the maximum flexure inopposite directions. The stillness in the .backward direction isillustrated in Figure 5, in which the deflection d at the middle of aspan of fourteen links is to On account of the limited pivotal movement,such a chain has the property that, when bent to a given radius, endthrust on the chain will cause it to bulge laterall with respect to thedirection of thrust, by virtue of a toggle action between links, whichis transmitted from link-to-link along the chain. Accordingly, for thepurposes of this specification and the appended claims, such a chainwill be termed a toggle-chain, by which is meant a series of thrustlinks pivoted serially end-to-end, so that endwise pressure on the chainwill cause the links to bulge with a toggle action, exerting a thrust ina direction transverse to said endwise pressure.

A pair of chains I3 is connected to an upper anchorage plate M, threadedto an extension I5 of the rod 9 above the enlargement Iii. The lowerends of the chains I3 are adjustably connected to This head comprisesthe expandable head 5. several parts. A carrier block It havinglaterally extendingjguide ribs I! has a swivel connection to theoperating element 7. This swivel connecdownward toward the head 6.

tion is formed by a pair of blocks l8 secured to the underside of theblock 16, and provided with inner ribs IS engaging a groove in theoperating element 7. This connection provides that, when the element Fis turned in the base 2, its threads cause it to move endwise in thatbase, thereby moving the head 6 toward or away from said base 2.

Mounted to slide on the ribs I! are two slide blocks 2|, each providedwith oppositely projecting pins 22. The pins 22 engage in cam slots 23in the side plates 3, so that, when the head 6 is moved toward or fromthe base 2, the slide blocks 2| will be moved outward or inward by thecam action of said pins and slots. Each slide block 2| is formed with awedge-shaped tooth 24 adapted to be engaged by the sprocket-teeth of oneof the chains i 3. The chain is secured in such engagement by a pair ofkeeper plates 25, fitting into slots in the slide block 2|, and securedby set screws 28 or the like. Each of the plates is provided withgrooves 21 adapted to receive the heads of the pivot pins of adjacentlinks of the chain.

By removal of one of the plates 25 on each of the respective slideblocks 2|, the position of engagement along the chains l3 may be shiftedto adapt the expander to pistons of widely differing skirt lengths. Inthis way, variation is made in the number of chain links between theanchorage plate l4 and the connection with head 6; the surplus chaindepending below the latter connection as shown at 28. The rod 9 passesfreely through a central bore in the carrier block I6, while the end ofthe sleeve 8 may abut against the lower face of said block to supportthe upward pull of the rod 9. A nut 29 may be positioned on the rod 9 tolimit its movement in the block Hi.

In the use of this device, the chains l3 are secured to the head 6 asdescribed, their length being adjusted to suit the piston to beexpanded. The expander is then inserted into the piston as shown inFigure 1, and the piston pin ll may be inserted into its bearings in thepiston, passing through the bore of the enlargement Ill. The operatingelement 8 may now be turned on the threaded rod 9 to draw the anchorageplate I4 This causes the chains [3 to bulge in the region of the upperportion of the skirt by the toggle action explained above. The element 8is turned until the outward thrust of. the bulging chains expands theupper portion of the skirt the desired amount. If

only the top of the skirt is to be expanded, the manipulation may stophere. If the lower portion of the skirt only is to be expanded, thechains may be bulged just sufliciently to contact the skirt, and thenthe head 6 may be expanded by operation of the element 1 until the skirtshows the desired expansion. It is often desirable to make the diametersof the upper and lower portions of the skirt difierent by a slightamount.

In such a case, the chains may be bulged until they just start to expandthe skirt, and then the head 6 adjusted to the desired difference indiam- .eter, after which both operative elements I and 8 may be operatedin unison to expand both upper and lower portions of the skirtsimultaneously. The elements 1 and 8 are provided ,with adjacent knurledmanipulating heads, as

shown in Figure 1, so that both may be grasped simultaneously andoperated in unison. When the-desired expansion has been obtained"- theexpander, with the piston on it, may be placed in any suitableheat-treating means whereby the expanded shape of the piston may berendered permanent.

In Figure 3, a piston having an internal rib 30 is shown. In such a casethe backward flexibility illustrated in Figure 5 makes it possible toexert full pressure on the piston at the bulge of the chains withoutexcessive pressure on the rib 30.

It will be seen, therefore, that this invention provides an expanderadaptable to almost any condition under which pistons are ordinarilyexpanded. The action of the toggle-chain is such that adequate lateralthrust can be applied to the piston, though the chain is flexible enoughto accommodate itself to different sizes of pistons. The vmanipulationof the chain and the expandable head 6 may be such as to control theexpanded shape of the piston to a high degree of precision, both as toactual dimensions and as to relative sizes of different parts of theskirt.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

1. An expander of the character described, comprising, upper and loweranchorages, a toggle chain connected to each of said anchorages, meansfor moving said anchorages rectilinearly relative to each other, one ofsaid anchorages being expandable transversely of the direction of saidrectilinear relative movement, and means for expanding said latteranchorage.

2. An expander of the character described, comprising, a supporting bodyhaving an expandable portion, an extensible element on said body. a pairof toggle-chains connected to said element and to the expandable portionof said body, means for moving said element and said body relatively todecrease and increase the rectilinear distance between the chainconnections and thereby to bulge or shrink said chains, and means forexpanding said expandable portion of said body.

3. An expander of the character described, comprising, a supporting bodyhaving an expandable portion, an extensible element on said body, a pairof toggle-chains connected to said element and to the expandable portionof said body, means for moving said element and said body relatively todecrease and increase the rectilinear distance between the chainconnections and thereby to bulge or shrink said chains, and means forexpanding said expandable portion of said body, said moving andexpanding means being operable separately for producing said bulging andexpanding adjustments separately, and in unison for producing saidadjustments simultaneously.

4. A piston expander having a part for interlocking with the piston tobe expanded, a pair of anchorages adjacent said part, a pair oftoggle-chains anchored one to each anchorage, a body member having ananchorage at each side thereof for connection respectively with saidchains, means for spreading apart the anchorages on the body member tovary the distance between the ends of different chains connected,thereto, and means for moving said body toward REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Mitchell Apr. 16, 1889 Haskin May12, 1914 Taylor Dec. 23, 1924 Dove Mar. 19, 1940 Oliver June 4, 1940Fries July 4, 1944

